Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".

However like snibgo has mentioned most of the time will be involved in the I/O of the image files. There are ways to make this faster, the best being to keep the images in memory until all your processing is complete, That is if you do have more processing of the images.

When the output is PNG, the "quality" does not affect image appearance; it only affects the amount of compression. For your task, try "-quality 50" or "-quality 40", then adjust until you are happy with the compression speed and filesize (put this option at the end, just before "result.png" on your commandline).